Biology- Finding new drugs

There are currently over 6000 different kinds of medicine available in the UK. But new drugs are needed because:

·New diseases are emerging.

·There are still some diseases for which there are no effective treatments.

·Some antibiotic treatments are becoming less effective – the microorganisms that cause disease continue to evolve. As soon as we start to use a new drug, it acts as a selection pressure. Any strain of microorganism that are less susceptible to, or are resistant to, the drug will be at a selective advantage. These resistant organisms are more likely to survive and reproduce, and the next generation will be more resistant.

How are drugs discovered?

By accident:

The accidental discovery of penicillin by Alexander Fleming is well documented. Most antibiotics currently in use are made by the bacterium Streptomyces. But streptomycin is now rarely used as most bacteria are resistant to it.

Traditional Medicine:

Many drugs have been used for centuries. The World Health Organisation calculates that 80% of the world’s population relies on traditional medicines. In India some 7000 plants are used for their medicinal properties, and in China they use about 5000 different plants. In Europe, too, some of our modern drugs have their origin in traditional medicine.

Anaesthetics:

The sap of unripe poppies was used in Neolithic times in parts of southern Europe and Egypt. In the twelfth century opium from poppies was used as an anaesthetic and by the nineteenth century morphine and opium were being used. These opiate drugs reduce nervous action in the central nervous system. If the nerves cannot carry impulses, no pain is felt.

Observation of wildlife:

There are many examples of animals self-medicating. For example:

·Monkeys, bears and other animals rub citrus oil onto their coats as insecticides and antiseptics to prevent insect bites and infection.

·Chimpanzees swallow leaves folded in a particular way to remove parasites from their digestive tract.